This invention relates to hydrodynamic torque converters such as are used with automotive vehicle transmissions and the like. More particularly, the invention relates to a hydraulic coupling member using channel inserts mounted to an outer shell to form fluid flow passages in a coupling member, such as a turbine or impeller.
It is known in the art to provide a hydrodynamic torque converter for an automotive transmission with coupling members, including an impeller and a turbine, which together with a stator include blades defining fluid circulation passages that transmit power from the impeller to the turbine for driving a vehicle. The passages are configured in a known manner so that engine torque delivered to the impeller is increased in the turbine when operating at lower speeds. The stator is mounted on a one way clutch so that the stator may rotate with the fluid flow as torque multiplication is reduced and the turbine speed increases to approach the rotational speed of the impeller.
Conventionally, the coupling members have been formed as castings or fabricated sheet metal members. A traditional sheet metal turbine assembly includes an inner shell, an outer shell and a plurality of stamped blades. During fabrication, the inner and outer shells are stamped and slotted. The blades are formed by multi-station stamping and stacked for assembly. An automatic blade setter inserts the blades serially into the outer shell. The inner shell is then assembled to the blades and the blade tabs are rolled down against the shell. Finally, the assembly is brazed to fill in gaps between the shells and the blades.
The present invention provides a converter coupling member having a simplified structure that can include plastic materials and permit a reduction in components with simplified assembly processes which may result in lighter components and reduced assembly costs. In the case of a turbine, the coupling is made with an outer shell and a plurality of channel inserts. The inserts form the curved channels or fluid passages of the turbine and include generally concentric curved inner and outer sides integrally connected to one another along one edge by a connecting wall that acts as a blade or vane. The inserts are secured in the outer shell with their outer sides against the outer shell. The inner sides are supported at both edges by the connecting walls, which are integral with one edge and include grooves for receiving the opposite unsupported edges. Thus, the inner sides close the channels inwardly and avoid the need for a separate inner shell in the improved assembly.
The channel inserts and the outer shell are preferably made from lightweight materials such as high temperature thermoplastics. However, suitable lightweight metals could be substituted if desired. To connect the inserts with the outer shell, the shell is perforated to receive plug-like appendages or pins extending from the outer sides of the inserts. The pins extend through the perforated openings and are swaged on the outer sides of the shell to fix them in place.
In one example of a turbine assembly according to the invention, the channel inserts are molded from a high temperature thermoplastic polyimide material. For a comparable turbine, the mass of the plastic channel inserts was found to be nearly 63 percent less than that of an equal number of stamped blades and the inner shell of a stamped metal turbine assembly which the channel inserts would replace. In another alternative, a polyamid material, such as DuPont(copyright) nylon 66, may be used for forming the channel inserts.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.